Packaging materials used for packaging contents are required to suppress quality deterioration of the contents. The quality deterioration of the contents may be accelerated by atmospheric gases permeating the packaging materials. Therefore, various laminated films are under development as materials for packaging bags, to suppress gas permeation from the atmosphere.
For example, Patent Literature 1 proposes a technique for improving gas barrier properties by providing a gas barrier deposited thin film layer and a gas barrier coated layer on a resin substrate. Patent Literature 2 proposes a technique for improving gas barrier properties of a packaging material by sequentially laminating a transparent primer layer, a deposited thin film layer, and a gas barrier composite film on one side of a polypropylene substrate.